[OpenLayers-Users] Re: Handler.Box units

[Puneet Kishor]

On Nov 2, 2011, at 5:46 PM, Puneet Kishor wrote:

> 
> On Nov 2, 2011, at 4:37 PM, Puneet Kishor wrote:
> 
>> I am reusing the sample code from the Handler.Box documentation
>> 
>> 	var control = new OpenLayers.Control();
>> 	OpenLayers.Util.extend(control, {
>> 		draw: function () {
>> 			// this Handler.Box will intercept the shift-mousedown
>> 			// before Control.MouseDefault gets to see it
>> 			this.box = new OpenLayers.Handler.Box(
>> 				control,
>> 				{done: this.notice},
>> 				{keyMask: OpenLayers.Handler.MOD_SHIFT}
>> 			);
>> 			this.box.activate();
>> 		},
>> 	
>> 		notice: function (bounds) {
>> 			OpenLayers.Console.userError("bounds: " + bounds);
>> 			var bbox = bounds.transform(proj.google, proj.latlng).toBBOX();
>> 			OpenLayers.Console.userError("bbox: " + bbox);
>> 		}
>> 	});
>> 	
> 
> I am doing something wrong here trying to convert pixels to lat lng
> 
> 	var bbox = bounds.toArray();
> 	var p1 = map.getLonLatFromPixel(bbox[0]);
> 	var str  = "Lat: " + p1.lat + " (Pixel.x:" + p1.x + ") Lon: " + p1.lon + " (Pixel.y:" + p1.y + ")\n";
> 	alert(str);
> 
> produces the following alert
> 
> 	Lat: NaN (Pixel.x:undefined) Lon: NaN (Pixel.y:undefined)
> 
> 


The following is my solution

	// 'p' is not really lon lat point even though it seems like one
	// actually it is pixel in image space
	var p = bounds.getCenterLonLat();
	var x = p.lon, y = p.lat;

	// 'pixel' is not really pixel, but is a point in base map coords
	// which, in this case, is in spherical mercator since my base map 
	// is a Google map
	var pixel = new OpenLayers.Pixel(x, y);

	// finally, a real lat lng point
	var ll = map.getLonLatFromPixel(pixel).transform(proj.google, proj.latlng);

The above works for me. It would, in my opinion, be useful to embellish the documentation with such information.

Many thanks,

--
Puneet Kishor